As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
FIG. 1 depicts selected elements of an example prior art information handling system 1. Information handling system 1 includes a host 10, which may include processing resources (e.g., one or more central processing units (CPUs) and storage resources that are accessible to the processing resources) in a housing 12. Storage resources may include volatile storage or memory and/or persistent storage, e.g., disk storage, flash memory or other type of erasable read only memory (ROM), and the like. Information handling system 1 may also include various other peripheral or I/O devices known in the field of data processing system design, such as mouse 14 and display 20 shown in FIG. 1.
Host 10 may include a keyboard 30. As shown in FIG. 1, keyboard 30 may include a set of keycaps (and/or buttons) 32 operable to provide input to host 10. One example of keyboard 30 includes a set of keycaps 32 arranged in the so-called “QWERTY” character set, which has been used for typewriters. In a standard keyboard 30, keycaps 32 display one or more imprinted characters, for example, characters corresponding to alphanumeric characters, mathematical functions, and/or specialized function keys.
Information handling system 1 may include a mobile information handling device, e.g., laptop 10 shown in FIG. 2 or any other type of mobile computing device (e.g., a tablet computer, a notebook computer, a PDA, a cellphone, etc.). Case 12 may include any chassis, cabinet, tower, box, and/or enclosure appropriate for housing information handling system 1. Display 20 may include any information display for visual presentation of images, texts, and/or other output from information handling system 1. Keyboard 30 may include any arrangement of buttons and/or keys designed for the input of text, characters, and/or operational controls for information handling system 1. Keyboard 30 may include individual keycaps 32.
Laptop 10 may also include processing resources, e.g., one or more central processing units (CPUs) and storage resources that are accessible to the processing resources. Storage resources may include volatile storage or memory and/or persistent storage, e.g., disk storage, flash memory or other type of erasable read only memory (ROM), and the like.
FIGS. 3 and 4a-4b show some of the construction details of a typical keyboard 30, including keycaps 32, a scissor mechanism 34, a cosmetic mask 36, a switch membrane 40, electronic circuit traces 42, a dome switch 44, a ribbon connector 46, and a base plate 50.
Base plate 50 is often made of metal and provides structure for keyboard 30. In addition, base plate 50 provides mounting points for other components of keyboard 30. Switch membrane 40 is disposed between base plate 50 and keycaps 32. Switch membrane 40 is often made of plastic film. Electronic circuit traces 42 are printed on the surface of switch membrane 40. Electronic circuit traces 42 are typically printed with silver ink onto switch membrane 40.
Dome switch 44 is a commonly used switch sometimes called a “direct-switch” mechanism. Dome switch 44 is positioned beneath keycap 32 and collapses between base plate 50 and keycap 32 when keycap 32 is depressed by a user. The inner surface of dome switch 44 is coated with an electrically conductive material, so when dome switch 44 collapses, the conductive material completes a circuit between electronic circuit traces 42 printed on switch membrane 40.
In keyboard 30 incorporating scissor mechanism 34, keycaps 32 are typically attached to keyboard 30 using two plastic arms that interlock like scissors. Scissor mechanism 34 snap connects to both keyboard 30 and keycap 32. Cosmetic mask 36 typically conceals portions of keyboard 30 from a user's line-of-sight.
FIG. 4b illustrates an example prior art switch membrane 40 with electronic circuit traces 42, dome switches 44, and ribbon connector 46 for use in keyboard 30. Switch membrane 40 includes a plurality of switches (e.g., dome switches 44). Ribbon connector 46 is an electrical connection between electronic circuit traces 42 and host 10 or information handling system 1. Switch membrane 40 is perforated as shown in FIG. 4b so that scissor mechanisms 34 can be connected to base plate 50 through the perforations.
FIG. 5 illustrates an example electroluminescent panel 60 (EL Panel) that is used to provide backlighting for some keyboards. EL Panel 60 includes holes 62 and a lead 64. In general, an electroluminescent panel typically includes two sheets of plastic film bonded together to form a capacitor. The space between the two sheets is typically filled with an electroluminescent material (e.g., powder phosphor, zinc sulfide, etc.). Electroluminescent materials emit light in response to an electric current passing through the material. EL Panel 60 emits light in response to application of current across the capacitor formed by the sheets of plastic film. EL Panel 60 is perforated with holes 62 so that scissor mechanisms 34 may connect keycaps 32 to base plate 50 and/or so that dome switches 44 may protrude through EL Panel 60. Lead 64 provides an electrical connection between EL Panel 60 and other portions of keyboard 30 to provide electric current to the electroluminescent material.
Other keyboards provide backlighting through the use of light emitting diodes (LED) that illuminate a large sheet by edge lighting. Such a solution, however, typically consumes a great deal of power and adds bulk and weight to a keyboard. LED solutions may not be satisfactory for use in a mobile information handling system where size and weight are important design parameters.